Need Help With Cupcakes

need help, making cupcakes but the they won't rise. the first dozen didn't rise in the center but I guessed more liquid was needed because the batter was really thick. the second dozen with more liquid added rose weakly. I was using the "Taste of Home" yellow cake recipe. It tastes good but the part of the cupcake that rises above the liner tears off easily the cake sticks to the liners. would adding an extra egg to the called for 2 eggs help?

the recipe is as follows:1 1/2 sticks butter1 3/4 C sugar2 eggs1 1/2 Tsp vanilla extract2 1/2 C all purpose flour2 1/2 tsp baking powder1/2 tsp salt1 1/4 C milkIn a large mixing bowl cream butter and sugar until light & fluffy. add eggs one at a time, beating well after each one. stir in vanilla. combine the flour baking powder and salt. ( I also added a small box vanilla pudding because I like a moist cake. I did this also the first time I fixed this recipe and it turned out fine.) add to the creamed mix alternately with milk. beating well after each addition. pour into 2 greased & floured 9" cake pans. bake at 350 degrees for 25-30 minutes or until test comes out clean. cool for 10 minutes then remove to wire racks to continue cooling.I bought new baking powder just before Christmas so I know it isn't expired ingredients. Should I have done something different when adding pudding to a cake recipe? should I do something different when using a cake recipe for cupcakes? I have been searching for a good from scratch cake recipe and thought I finally found it.

do you live at a high altitude? if so that may be playing a part in your cupcakes not rising. you may need to altitude adjust your recipe. however, i think i would try making the batter without the pudding and see what happens. they should be moist, even without the pudding.